DESCRIPTION: The long term objective of the proposed research is to discover the changing behavioral roles which parallel the evolution of sensory, association, and motor cortex in the historical lineage leading to Primates and Man. The general strategy begins with a description of the structure-function relationships of major areas of neocortex in a number of neurologically generalized mammals specifically selected for their sequential common ancestry with Primates. The methods have included cytoarchitectonic and anatomical tract-tracing techniques to determine the successive changes in the location, extent, and connections of sensory and motor areas and then receptor-binding and immunohistochemical techniques for neurotransmitter-identification of the afferents and efferents for the same areas. The results of these structural studies are then used to guide comparative behavioral studies and ablation-behavior experiments to determine the history of the behavioral contributions of the several areas. In this manner the evolutionary development of the neocortex is traced from its most primitive mammalian form to the Primate form in an attempt to understand the contributions of its many parts. In this application they focus on the behavioral consequences of the three most radical evolutionary changes in form which have been already uncovered.